Vinyl modifier composition and processes for utilizing such composition

ABSTRACT

An oxolanyl compound-containing composition comprising specified amounts of the meso-isomer of one or more of the oxolanyl compounds of specified structure is provided. Also provided are methods for the use of such compositions as vinyl content modifiers in polymerization processes.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/518,711 which claims priority to and benefit of PCT Application No.PCT/US2010/061795 filed Dec. 22, 2010, which claims priority to andbenefit of U.S. Provisional Application No. 61/288,900 filed Dec. 22,2009, the entire disclosures of which are incorporated by referenceherein.

FIELD OF INVENTION

The embodiments relate to an oxolanyl compound-containing compositioncomprising specified amounts of the meso-isomer of one or more of theoxolanyl compounds of specified structure and the use of suchcompositions as vinyl content modifiers in polymerization processes.

BACKGROUND

Oligomeric oxolanyl compounds have been utilized as microstructure(1,2-vinyl content) modifiers in the preparation of (co)polymers havinga 1,2-microstructure of between 10 and 95 percent from a monomer systemwhich contains at least one conjugated diene monomer. Certain of theseoxolanyl compounds have at least two chiral centers that result in theexistence of D, L and meso stereoisomers. Commercially availablecompositions of oxolanyl compounds such as2,2-di(2-tetrahydrofuryl)propane contain a mixture of approximately 50%D, L isomers and approximately 50% of the meso isomer.

SUMMARY OF THE INVENTION

The embodiments disclosed herein relate to an oxolanylcompound-containing composition comprising specified amounts of themeso-isomer of one or more of the oxolanyl compounds of specifiedstructure. The at least one oxolanyl compound present in the compositionis selected from the group consisting of:

wherein R₁ and R₂ independently are hydrogen or an alkyl group and thetotal number of carbon atoms in —CR₁R₂— ranges between one and nineinclusive; R₃, R₄ and R₅ independently are —H or —C_(n)H_(2n+1) whereinn=1 to 6. The composition comprises at least 52% by weight of themeso-isomer of the at least one oxolanyl compound.

Additional embodiments include a polymerization process for producing apolydiene polymer comprising polymerizing at least one conjugated dienemonomer in the presence of a composition comprising at least oneoxolanyl compound selected from the group consisting of:

wherein R₁ and R₂ independently are hydrogen or an alkyl group and thetotal number of carbon atoms in —CR₁R₂— ranges between one and nineinclusive; R₃, R₄ and R₅ independently are —H or —C_(n)H_(2n+1) whereinn=1 to 6. The composition comprises at least 52% by weight of themeso-isomer of the at least one oxolanyl compound.

Additional embodiments include a relatively high temperaturepolymerization process comprising polymerizing 1,3-butadiene in thepresence of the oxolanyl compound 2,2-di(2-tetrahydrofuryl)propane wherethe oxolanyl compound comprises at least 52% by weight of themeso-isomer. Such a process produces a polydiene polymer with a vinylcontent between 10 and 65%, includes the use of an organolithium anionicinitiator, and is conducted at a temperature between 85° C. and 120° C.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a plot of concentration of the oxolanyl compound versusvinyl content in the resulting polybutadiene.

FIG. 2 shows a plot of concentration of the oxolanyl compound versusvinyl content in the resulting polybutadiene.

FIG. 3 shows a ¹H NMR of meso-2,2-ditetrahydrofurylpropane.

FIG. 4 shows a ¹H NMR of D, L-2,2-ditetrahydrofurylpropane.

FIG. 5 shows a plot of vinyl content as a function of ppm DTHFP atvarious meso DTHFP concentrations.

FIG. 6 shows a plot of weight percent butadiene of the reaction mixtureover time and the temperature of the reaction mixture over time.

DETAILED DESCRIPTION

The present disclosure relates to an oxolanyl compound-containingcomposition comprising a specified amount of the meso-isomer of one ormore of the oxolanyl compounds of specified structure and the use ofsuch compositions as vinyl content modifiers in polymerizationprocesses. It has unexpectedly been found that the meso-isomer is moreactive than the commercially available and previously-utilized mixtureof D, L and meso when used as a vinyl content modifier in polymerizationreactions. Increased activity of the meso-isomer allows for use ofrelatively less of the oxolanyl compound to achieve the same result asthe commercially available mixture of D, L and meso isomers.Commercially available compositions of oxolanyl compounds such as2,2-di(2-tetrahydrofuryl)propane contain a mixture of approximately 50%(i.e., 50%+/−1%) D, L isomers and approximately 50% (i.e., 50%+/−1%)meso isomer.

Embodiments disclosed herein relate to an oxolanyl compound-containingcomposition comprising at least 52% by weight of the meso-isomer of oneor more of the oxolanyl compounds. The at least one oxolanyl compound isselected from the group consisting of:

wherein R₁ and R₂ independently are hydrogen or an alkyl group and thetotal number of carbon atoms in —CR₁R₂— ranges between one and nineinclusive; R₃, R₄ and R₅ independently are —H or —C_(n)H_(2n+1) whereinn=1 to 6. The composition comprises at least 52% by weight of themeso-isomer of the at least one oxolanyl compound, with the remainderbeing comprised of the D and L stereoisomers. In other embodiments, thecomposition comprises at least 55%, 60%, at least 75%, at least 90% or100% by weight of the meso-isomer. In certain embodiments, thecomposition comprises only one oxolanyl compound, and in otherembodiments, it comprises two, three or more different oxolanylcompounds. In certain embodiments the at least one oxolanyl compoundscomprises 2,2-di(2-tetrahydrofuryl) propane.

In certain embodiments, the composition comprising at least one oxolanylcompound selected from the above-specified group may be a purifiedmixture resulting from the separation of a mixture of the D, L and mesoforms of the oxolanyl compound by known techniques such as columnchromatography or fractional distillation. It is specificallycontemplated that other separation techniques, both those currentlyknown and others developed in the future, may be utilized to achieve acomposition that contains the specified amount of the meso-isomer of theat least one oxolanyl compound. In other embodiments, the meso-isomermay be preferentially produced during the synthesis of the at least oneoxolanyl compound.

Additional embodiments include a polymerization process for producing apolydiene polymer comprising polymerizing at least one conjugated dienemonomer in the presence of a composition comprising at least oneoxolanyl compound selected from the group consisting of:

wherein R₁ and R₂ independently are hydrogen or an alkyl group and thetotal number of carbon atoms in —CR₁R₂— ranges between one and nineinclusive; R₃, R₄ and R₅ independently are —H or —C_(n)H_(2n+1) whereinn=1 to 6. Various 1,3-diene monomers, as discussed below, may beutilized in the process. The composition comprises at least 52% byweight of the meso-isomer of the at least one oxolanyl compound, withthe remainder being comprised of the D and L stereoisomers. In otherembodiments, the composition comprises at least 55%, 60%, at least 75%,at least 90% or 100% by weight of the meso-isomer. In certainembodiments, the composition comprises only one oxolanyl compound, andin other embodiments, it comprises two, three or more different oxolanylcompounds. In certain embodiments the at least one oxolanyl compoundcomprises 2,2-di(2-tetrahydrofuryl) propane.

The polymerization process may optionally include the copolymerizationof at least one additional monomer, including, but not limited to, atleast one vinyl aromatic monomer along with the at least one conjugateddiene monomer. Various vinyl aromatic monomers, as discussed below, maybe utilized in the process. The resulting polydiene copolymer may takevarious forms including, but not limited to, random copolymers and blockcopolymers. In certain embodiments, the copolymer is a block copolymerof polybutadiene, polystyrene, and optionally polyisoprene. Inparticular embodiments, the (co)polymer is hydrogenated or partiallyhydrogenated.

The block copolymers can include at least one polyvinyl aromatic blockand at least one polydiene block. In one embodiment, the polydiene blockis characterized by a relatively high vinyl content. In one or moreembodiments, the block copolymers may be defined by the formula I:α-V-D-ω′where V is a polyvinyl aromatic block, D is a polydiene block, a and co′are each independently a hydrogen atom, a functional group, or apolymeric segment or block, and where D is characterized by a vinylcontent of at least 50%.

In one or more embodiments, polyvinyl aromatic blocks include three ormore mer units deriving from the polymerization of vinyl aromaticmonomer. In one or more embodiments, functional groups include organicor inorganic moieties that include at least one heteroatom. In one ormore embodiments, polymeric segments include homopolymers or copolymers.

In one or more embodiments, D of formula I is characterized by a vinylcontent (i.e., the percentage of mer units positioned in the1,2-microstructure) of at least 10%, in other embodiments of at least50%, in other embodiments at least 55%, in other embodiments at least60%, in other embodiments at least 65%, in other embodiments at least70%, in other embodiments at least 75%, in other embodiments at least80%, and in other embodiments at least 85%. In these or otherembodiments, D of formula I is characterized by a vinyl content of lessthan 100%, in other embodiments less than 95%, in other embodiments lessthan 90%, in other embodiments less than 85%, and in other embodimentsless than 80%. The vinyl content may be determined by proton NMR, and asreported herein refers to the percentage of mer units positioned in the1,2-microstructure based on the total mer units deriving from thepolymerization of conjugated diene monomer.

In one or more embodiments, the D block of formula I includes at least250, in other embodiments at least 350, in other embodiments at least450, and in other embodiments at least 550 mer units deriving from thepolymerization of conjugated diene monomer. In these or otherembodiments, the D block of formula I includes less than 800, in otherembodiments less than 750, in other embodiments less than 700, in otherembodiments less than 650, and in other embodiments less than 600 merunits deriving from the polymerization of conjugated diene monomer.

In one or more embodiments, the V block copolymer of formula I includesat least 50, in other embodiments at least 120, in other embodiments atleast 145, in other embodiments at least 160, in other embodiments atleast 180, in other embodiments at least 200, and in other embodimentsat least 225 mer units deriving from the polymerization of vinylaromatic monomer. In these or other embodiments, the V block of formulaI includes less than 400, in other embodiments less than 350, in otherembodiments less than 325, in other embodiments less than 300, and inother embodiments less than 280 mer units deriving from thepolymerization of vinyl aromatic monomer.

In one or more embodiments, the block copolymers defined by the formulaI are characterized by low levels of tapering, which may also bereferred to as randomness between the blocks of the polymer chain. Inother words, and for example, a vinyl aromatic block (e.g., polystyreneblock) of the block copolymer will have a limited number, if any, of merunits deriving from conjugated diene (e.g., 1,3-butadiene) within theblock. For purposes of this specification, tapering will refer to thelevel or amount of mer emits (in moles) present within a given block asan impurity in that block (e.g., styrene mer units within apolybutadiene block). In one or more embodiments, the blocks of theblock copolymers defined by the formula I include less than 5%, in otherembodiments less than 3%, in other embodiments less than 1%, and inother embodiments less than 0.5% tapering in any given block of theblock copolymer. In these or other embodiments, the blocks of the blockcopolymers defined by the formula I are substantially devoid oftapering, which includes that amount of tapering or less that will nothave an appreciable impact on the block copolymer. In one or moreembodiments, the blocks of the block copolymers defined by the formula Iare devoid of tapering.

In one or more embodiments, α is a diene block deriving from thepolymerization of diene monomer, and therefore the block copolymer canbe defined by the formula IId-V-D-ω′where d is a polydiene block deriving from the polymerization of dienemonomer, V, D, and ω′ are as defined above with respect to formula I,and where D and d are characterized by a vinyl content of at least 50%.

In one or more embodiments, d of formula II is characterized by a vinylcontent (i.e., the percentage of mer units positioned in the1,2-microstructure) of at least 10%, in other embodiments of at least50% in other embodiments at least 55%, in other embodiments at least60%, in other embodiments at least 65%, in other embodiments at least70%, in other embodiments at least 75%, in other embodiments at least80%, and in other embodiments at least 85%. In these or otherembodiments, D is characterized by a vinyl content of less than 100%, inother embodiments less than 95%, in other embodiments less than 90%, inother embodiments less than 85%, and in other embodiments less than 80%.

In one or more embodiments, d of formula II includes at least 10, inother embodiments at least 40, in other embodiments at least 60, and inother embodiments at least 80, in other embodiments at least 100, and inother embodiments at least 120 mer units deriving from thepolymerization of conjugated diene monomer. In these or otherembodiments, d of formula II includes less than 500, in otherembodiments less than 350, in other embodiments less than 250, in otherembodiments less than 200, in other embodiments less than 180, in otherembodiments less than 160, and in other embodiments less than 120 merunits deriving from the polymerization of conjugated diene monomer.

In one or more embodiments, the blocks of the block copolymers definedby the formula II include less than 5%, in other embodiments less than3%, in other embodiments less than 1%, and in other embodiments lessthan 0.5% tapering in any given block of the block copolymer. In theseor other embodiments, the blocks of the block copolymers defined by theformula II are substantially devoid of tapering, which includes thatamount of tapering or less that will not have an appreciable impact onthe block copolymer. In one or more embodiments, the blocks of the blockcopolymers defined by the formula III are devoid of tapering.

In one or more embodiments the block copolymers may be defined by theformula IIIα-V^(o)-D-V′-ω′where each V is independently a polyvinyl aromatic block, D is apolydiene block, a and ω′ are each independently a hydrogen atom, afunctional group, or a polymeric segment or block, and where D ischaracterized by a vinyl content of at least 50%.

In one or more embodiments, D of formula III is characterized by a vinylcontent (i.e., the percentage of mer units positioned in the1,2-microstructure) of at least 10%, in other embodiments of at least50%, in other embodiments at least 55%, in other embodiments at least60%, in other embodiments at least 65%, in other embodiments at least70%, in other embodiments at least 75%, in other embodiments at least80%, and in other embodiments at least 85%. In these or otherembodiments, D is characterized by a vinyl content of less than 100%, inother embodiments less than 95%, in other embodiments less than 90%, inother embodiments less than 85%, and in other embodiments less than 80%.

In one or more embodiments, the D of formula III includes at least 250,in other embodiments at least 350, in other embodiments at least 450,and in other embodiments at least 550 mer units deriving from thepolymerization of conjugated diene monomer. In these or otherembodiments, the D block of formula III includes less than 800, in otherembodiments less than 750, in other embodiments less than 700, in otherembodiments less than 650, and in other embodiments less than 600 merunits deriving from the polymerization of conjugated diene monomer.

In one or more embodiments, the V^(o) and V′ blocks of formula III eachindependently include at least 25, in other embodiments at least 60, inother embodiments at least 75, in other embodiments at least 80, inother embodiments at least 90, in other embodiments at least 100, and inother embodiments at least 115 mer units deriving from thepolymerization of vinyl aromatic monomer. In these or other embodiments,V^(o) and V′ each independently include less than 200, in otherembodiments less than 175, in other embodiments less than 160, in otherembodiments less than 150, and in other embodiments less than 140 merunits deriving from the polymerization of vinyl aromatic monomer.

In one or more embodiments, the ratio of V^(o) mer units to V′ mer unitsis at least 0.2:1, in other embodiments at least 0.4:1, in otherembodiments at least 0.6:1, in other embodiments 0.8:1, in otherembodiments at least 0.9:1, and in other embodiments at least 0.95:1. Inthese or other embodiments, the ratio of V^(o) mer units to V′ mer unitsis less than 4:1, in other embodiments less than 3:1, in otherembodiments less than 2:1, in other embodiments less than 1.5:1, inother embodiments less than 1.1:1, and in other embodiments less than1.05:1. In one or more embodiments, the ratio of V^(o) mer units to V′mer units is about 1:1.

In one or more embodiments, the blocks of the block copolymers definedby the formula III include less than 5%, in other embodiments less than3%, in other embodiments less than 1%, and in other embodiments lessthan 0.5% tapering in any given block of the block copolymer. In theseor other embodiments, the blocks of the block copolymers defined by theformula III are substantially devoid of tapering, which includes thatamount of tapering or less that will not have an appreciable impact onthe block copolymer. In one or more embodiments, the blocks of the blockcopolymers defined by the formula III are devoid of tapering.

In one or more embodiments, α of formula III is a diene block, andtherefore the block copolymer can be defined by the formula IVd-V^(o)-D-V′-ω′where d is a polydiene block, V^(o), V′, D, and ω′ are as defined abovewith respect to Formula III, and where D and d are characterized by avinyl content of at least 50%.

In one or more embodiments, d of formula IV is characterized by a vinylcontent (i.e., the percentage of mer units positioned in the1,2-microstructure) of at least 10%, in other embodiments of at least50%, in other embodiments at least 55%, in other embodiments at least60%, in other embodiments at least 65%, in other embodiments at least70%, in other embodiments at least 75%, in other embodiments at least80%, and in other embodiments at least 85%. In these or otherembodiments, d of formula IV is characterized by a vinyl content of lessthan 100%, in other embodiments less than 95%, in other embodiments lessthan 90%, in other embodiments less than 85%, and in other embodimentsless than 80%. In one or more embodiments, d of formula IV includes atleast 10, in other embodiments at least 40, in other embodiments atleast 60, and in other embodiments at least 80, in other embodiments atleast 100, and in other embodiments at least 120 mer units deriving fromthe polymerization of conjugated diene monomer. In these or otherembodiments, d of formula IV includes less than 500, in otherembodiments less than 350, in other embodiments less than 250, in otherembodiments less than 200, in other embodiments less than 180, in otherembodiments less than 160, and in other embodiments less than 120 merunits deriving from the polymerization of conjugated diene monomer.

In one or more embodiments, the peak molecular weight (Mp) of theoverall block copolymers may be at least 40 kg/mole, in otherembodiments at least 50 kg/mole, in other embodiments at least 60kg/mole, and in other embodiments at least 70 kg/mole. In these or otherembodiments, the overall peak molecular weight of the block copolymersmay be less than 150 kg/mole, in other embodiments less than 125kg/mole, in other embodiments less than 100 kg/mole, and in otherembodiments less than 90 kg/mole.

In one or more embodiments, the overall vinyl content of the blockcopolymers may be at least 10%, in other embodiments at least 50%, inother embodiments at least 55%, in other embodiments at least 60%, inother embodiments at least 65%, in other embodiments at least 70%, inother embodiments at least 75%, in other embodiments at least 80%, andin other embodiments at least 85%. In these or other embodiments, d offormula IV is characterized by a vinyl content of less than 100%, inother embodiments less than 95%, in other embodiments less than 90%, inother embodiments less than 85%, and in other embodiments less than 80%.As those skilled in the art will appreciate, the overall vinyl contentof the block copolymers can be tailored by adjusting the vinyl contentof particular diene blocks. For example, where the block copolymers aredefined by the formulae II and IV, the vinyl content of the d block canbe increased, without necessarily providing a corresponding increase tothe D block, to affect an overall increase in the vinyl content of blockcopolymer.

In one or more embodiments, the blocks of the block copolymers definedby the formula IV include less than 5%, in other embodiments less than3%, in other embodiments less than 1%, and in other embodiments lessthan 0.5% tapering in any given block of the block copolymer. In theseor other embodiments, the blocks of the block copolymers defined by theformula IV are substantially devoid of tapering, which includes thatamount of tapering or less that will not have an appreciable impact onthe block copolymer. In one or more embodiments, the blocks of the blockcopolymers defined by the formula IV are devoid of tapering.

In one or more embodiments, the block copolymers can be synthesized byemploying anionic polymerization techniques. In one or more embodiments,living polymers include anionically polymerized polymers (i.e., polymersprepared by anionic polymerization techniques). Anionically-polymerizedliving polymers may be formed by reacting anionic initiators withcertain unsaturated monomers to propagate a polymeric structure.Throughout formation and propagation of the polymer, the polymericstructure may be anionic or “living.” A new batch of monomersubsequently added to the reaction can add to the living ends of theexisting chains and increase the degree of polymerization. A livingpolymer, therefore, includes a polymeric segment having a living orreactive end. Anionic polymerization is further described in GeorgeOdian, Principles of Polymerization, ch. 5 (3^(rd) Ed. 1991), or Panek,94 J. Am. Chem. Soc., 8768 (1972), which are incorporated herein byreference.

In one or more embodiments, the block copolymers can be prepared bysequential addition of the distinct monomer that give rise to thevarious blocks. For example, vinyl aromatic monomer can be charged andpolymerized to form a living polyvinyl aromatic living polymer chain.After the vinyl aromatic monomer is consumed or substantially consumed,the conjugated diene monomer can be charged. The conjugated dienemonomer adds to the living polyvinyl aromatic chain and forms apolydiene block tethered thereto. After the diene monomer is consumed orsubstantially consumed, additional monomer can be added to form anotherblock tethered to the copolymer. For example, vinyl aromatic monomer canbe charged to form another vinyl aromatic block. This process can becontinued until the living polymer is quenched (e.g. protonated).

The process can be started by employing an anionic polymerizationinitiator, although as those skilled in the art appreciate, other meanscan be employed to initiate the polymerization.

In order to achieve the desired vinyl content of the polydiene blocks,polymerization of the diene monomer can be conducted in the presence ofthe oxolanyl compound-containing compositions described herein whilemaintaining the polymerization medium below certain thresholdtemperatures.

In one or more embodiments, the polymerization of the polydiene blocks(i.e., D and d) is conducted by setting the initial batch temperature(i.e., the temperature of the polymerization medium at the beginning ofthe polymerization of diene monomer) at temperatures below 30° C., inother embodiments below 25° C., in other embodiments below 20° C., inother embodiments below 15° C., and in other embodiments below 12° C. Inthese or other embodiments, the initial batch temperature may be set atabove −10° C., in other embodiments above 0° C., and in otherembodiments above 5° C.

In one or more embodiments, the temperature of the polymerization mediumduring the polymerization of conjugated diene monomer (i.e., during theformation of the polydiene blocks D or d) is maintained so as to achievea peak polymerization temperature below 60° C., in other embodimentsbelow 55° C., in other embodiments below 50° C., in other embodimentsbelow 48° C., in other embodiments below 45° C., in other embodimentsbelow 40° C., in other embodiments below 35° C., and in otherembodiments below 30° C. As those skilled in the art appreciate, theinitial batch temperature, as well as the peak polymerizationtemperature, can be controlled by employing several techniques, as wellas combinations thereof. For example, the jacket temperature can beadjusted, reflux condensers can be employed, particular solvents can beselected, and the solids concentration of the polymerization can beadjusted. It has unexpectedly been discovered that the use ofbis-oxolanyl propane and oligomers thereof as vinyl modifiers in theproduction of the block copolymers advantageously allows for peakpolymerization temperatures that are relatively high and yet achieve thebenefits of relatively high vinyl polydienes blocks. As those skilled inthe art will appreciate, this is extremely advantageous because itallows for the production of the block copolymers at relatively highrates of polymerization yielding relatively high volume of polymer,which makes production of the block copolymers commercially viable. Forexample, in one or more embodiments, polymerization of the D block orblocks of the block copolymers of one or more embodiments (e.g., thepolydienes blocks) can be allowed to achieve a peak polymerizationtemperature of at least 18° C., in other embodiments least 20° C., inother embodiments at least 23° C., in other embodiments at least 25° C.,in other embodiments at least 27° C., and in other embodiments at least30° C. In these or other embodiments, particularly where blockcopolymers include a diene block d (such as in formula II or IV), it hasunexpectedly been discovered that advantages can be achieved bymaintaining lower peak polymerization temperatures than maintainedduring polymerization of the D blocks. For example, in one or moreembodiments, the peak polymerization temperature achieved duringpolymerization of the d block is at least at least 5° C., in otherembodiments least 8° C., in other embodiments at least 10° C., in otherembodiments at least 12° C., in other embodiments at least 15° C., andin other embodiments at least 18° C. In these or other embodiments, thepeak polymerization temperature achieved during polymerization of the dblock is less than 35° C., in other embodiments less than 30° C., inother embodiments less than 27° C., in other embodiments less than 25°C., and in other embodiments less than 22° C.

In one or more embodiments, it has been unexpectedly discovered that bymaintaining the solids concentration of the polymerization medium duringformation of the polydienes blocks defined by D (in the formulae above)at particular concentrations, benefits are realized in terms of anadvantageous product produced at commercially viable rates and volumes.For example, in one or more embodiments, the solids content of thepolymerization medium during formation of the D blocks is maintained atlevels of at least 6%, in other embodiments at least 7%, in otherembodiments at least 8%, in other embodiments at least 9%, in otherembodiments at least 10%, in other embodiments at least 11%, and inother embodiments at least 12%. In these or other embodiments, thesolids content of the polymerization medium during formation of the Dblock is maintained at levels below 22%, in other embodiments below 20%,in other embodiments below 18%, in other embodiments below 15%, and inother embodiments below 13%. Similarly, it has been unexpectedlydiscovered that by maintaining the solids concentration of thepolymerization medium during formation of the polydienes blocks definedby d (in the formulae above) at particular concentrations, benefits arerealized in terms of an advantageous product produced at commerciallyviable rates and volumes. For example, in one or more embodiments, thesolids content of the polymerization medium during formation of the dblocks is maintained at levels of at least 0.5%, in other embodiments atleast 1%, in other embodiments at least 2%, in other embodiments atleast 3%, in other embodiments at least 4%, in other embodiments atleast 5%, and in other embodiments at least 6%. In these or otherembodiments, the solids content of the polymerization medium duringformation of the d block is maintained at levels below 8%, in otherembodiments below 7%, in other embodiments below 6%, in otherembodiments below 5%, and in other embodiments below 4%.

The polymerization can be carried out as a batch process, a continuousprocess, or a semi-continuous process. In one or more embodiments,conditions may be controlled to conduct the polymerization under apressure of from about 0.1 atmosphere to about 50 atmospheres, in otherembodiments from about 0.5 atmosphere to about 20 atmosphere, and inother embodiments from about 1 atmosphere to about 10 atmospheres. Inthese or other embodiments, the polymerization mixture may be maintainedunder anaerobic conditions.

As those skilled in the art will appreciate, the solids content of thepolymerization medium and the peak polymerization temperatures achievedduring formation of the vinyl aromatic blocks V can be adjusted toachieve maximum efficiency without impact the vinyl content of thepolydiene blocks.

In one or more embodiments, production of block copolymers occurs attechnologically useful rates of production. For example, in one or moreembodiments, when operating at the solids contents provided for hereinfor the polydienes blocks, conversion of at least 90% of the monomer tobe polymerized is achieved within at least 8 hours, in other embodimentsat least 6 hours, in other embodiments at least 5, in other embodimentsat least 4 hours, and in other embodiments at least 3 hours. In one ormore embodiments, an overall conversion of monomer is achieved attechnologically useful levels; for example, conversions of at least 90%,in other embodiments at least 92%, in other embodiments at least 95%, inother embodiments at least 97%, and in other embodiments at least 99% ofthe monomer charged is achieved when operating at the conditionsprovided for herein.

In one or more embodiments, a quenching agent can be added to thepolymerization mixture in order to inactivate residual living polymerchains. An antioxidant may be added along with, before, or after theaddition of the quenching agent. The amount of the antioxidant employedmay be in the range of, for example, 0.2% to 1% by weight of the polymerproduct. In one or more embodiments, a functionalizing or coupling agentmay be used in lieu of or together with a quenching agent.

When the polymerization mixture has been quenched, the polymer productcan be recovered from the polymerization mixture by using anyconventional procedures of desolventization and drying that are known inthe art. For instance, the polymer can be recovered by subjecting thepolymer cement to steam desolventization, followed by drying theresulting polymer crumbs in a hot air tunnel. Alternatively, the polymermay be recovered by directly drying the polymer cement. The content ofthe volatile substances in the dried polymer can be below 1%, and inother embodiments below 0.5% by weight of the polymer.

The characteristics of the resultant (co)polymer can vary greatly byemploying techniques that are well known in the art. The relativeamounts of the at least one conjugated diene monomer and the at leastone vinyl aromatic monomer present in the resulting (co)polymer can varywidely. In certain embodiments, the amount of the at least oneconjugated diene monomer present in the co(polymer) ranges from 100% to1% by weight. In other embodiments, the amount of the at least oneconjugated diene monomer ranges from 100% to 10% by weight, from 100% to15% by weight, from 100% to 20% by weight, or from 90% to 60% by weight.

The polydiene (co)polymer resulting from the polymerization process canhave a varying vinyl content (1,2-vinyl content), including, but notlimited to, ranging generally from 10% to less than 100%. In certainembodiments (such as relatively high temperature processes), the vinylcontent of the resulting polydiene (co)polymer is 10% to 65%, at least45%, 45% to 90%, at least 60% or 60% to 90%, or less than 100%. In otherembodiments, the vinyl content of the resulting polydiene (co)polymercan be at least 50%, at least 55%, at least 70%, at least 75%, at least80%, at least 85%, less than 95%, less than 90%, less than 85% or lessthan 80%.

The polydiene (co)polymer resulting from the polymerization processesdescribed herein can have varying Mw (weight average molecular weight)and Mn (number average molecular weight). The (co)polymer will have anumber average molecular weight of from 50 to 2,000 kg/mole, andpreferably from 50 to 300 kg/mole as measured by using gel permeationchromatography (GPC) calibrated with polystyrene standards and adjustedfor the Mark-Houwink constants for the polymer in questions. Themolecular weight distribution of the (co)polymer (Mw/Mn) (also known asthe polydispersity) is preferably less than 2, more preferably less than1.5, and even more preferably less than 1.3.

In certain embodiments, the polymerization process also includes the useof at least one organometallic anionic initiator. Various organometallicanionic initiators, as discussed below, may be utilized in the process.

In certain embodiments, the meso-isomer of the oxolanyl compound isutilized in a specific molar ratio with respect to the organometallicanionic initiator. Such ratios include, but are not limited to, 0.01:10to 0.05:5, 0.1:1, 0.1:0.7, and 1:1 (or described differently from0.001:1 to 0.14:1, including 0.001:1, 0.01:1, 0.1:1, 0.14:1, and 1:1).

In general, the polymerization process is conducted under conditions andusing reactants well known to those of ordinary skill in the art.Examples of such conditions and reactants are provided below, and shouldbe interpreted as exemplary only and in no way limiting.

Conjugated dienes that may be utilized in the polymerization processesinclude, but are not limited to, 1,3-butadiene, isoprene,1,3-pentadiene, 1,3-hexadiene, 2,3-dimethyl-1,3-butadiene,2-ethyl-1,3-butadiene, 2-methyl-1,3 pentadiene, 3-methyl-1,3-pentadiene,4-methyl-1,3-pentadiene, and 2,4-hexadiene. Mixtures of two or moreconjugated dienes may also be utilized in co-polymerization. Thepreferred conjugated dienes are 1,3-butadiene, isoprene, 1,3-pentadiene,and 1,3-hexadiene.

Aromatic vinyl monomers that may be utilizes in the polymerizationprocesses include, but are not limited to, styrene, α-methyl styrene,p-methylstyrene, and vinylnaphthalene.

Anionic polymerization initiators for use in the polymerizationsprocesses include, but are not limited to, organosodium,organopotassium, organomagnesium, organotin-lithium, and organolithiuminitiators. As an example of such initiators, organo-lithium compoundsuseful in the polymerization of 1,3-diene monomers are hydrocarbyllithium compounds having the formula RLi, where R represents ahydrocarbyl group containing from one to 20 carbon atoms and, suitably,from 2 to 8 carbon atoms. Although the hydrocarbyl group is preferablyan aliphatic group, the hydrocarbyl group can also be cycloaliphatic oraromatic. The aliphatic group can be a primary, secondary, or tertiarygroup, although the primary and secondary groups are most suitable.Examples of aliphatic hydrocarbyl groups include methyl, ethyl,n-propyl, isopropyl, n-butyl, sec-butyl, t-butyl, n-amyl, sec-amyl,n-hexyl, sec-hexyl, n-heptyl, n-octyl, n-nonyl, n-dodecyl, andoctadecyl. The aliphatic group can contain some unsaturation, such asallyl, 2-butenyl, and the like. Cycloalkyl groups are exemplified bycyclohexyl, methylcyclohexyl, ethylcyclohexyl, cycloheptyl,cyclopentylmethyl, and methylcyclopentylethyl. Examples of aromatichydrocarbyl groups include phenyl, tolyl, phenylethyl, benzyl, naphthyl,phenyl cyclohexyl, and the like.

Specific examples of organolithium compounds which are useful as anionicinitiators in the polymerizations include, but are not limited to,n-butyl lithium, n-propyl lithium, iso-butyl lithium, tert-butyllithium, tributyl tin lithium (described in co-owned U.S. Pat. No.5,268,439), amyl-lithium, cyclohexyl lithium, and the like. Othersuitable organolithium compounds for use as anionic initiators are wellknown to those skilled in the art. A mixture of different lithiuminitiator compounds also can be employed. Typical and suitableorgano-lithium initiators are n-butyl lithium, tributyl tin lithium and“in situ” produced lithium hexamethyleneimide initiator prepared byreacting hexamethyleneimine and n-butyl lithium (described in co-ownedU.S. Pat. No. 5,496,940).

In one or more embodiments, the functional initiator includes alithiated thioacetal such as a lithiated dithiane. Lithiated thioacetalsare known and include those described in U.S. Pat. Nos. 7,153,919,7,319,123, 7,462,677, and 7,612,144, which are incorporated herein byreference.

In one or more embodiments, the thioacetal initiators employed can bedefined by the formula

where each R⁶ independently includes hydrogen or a monovalent organicgroup, R⁰ includes a monovalent organic group, z is an integer from 1 toabout 8, and ω includes sulfur, oxygen, or tertiary amino (NR, where Ris an organic group).

In one or more embodiments, the functional initiators may be defined bythe formula

where R⁰ includes a monovalent organic group.

Specific examples of functional initiators include2-lithio-2-phenyl-1,3-dithiane,2-lithio-2-(4-dimethylaminophenyl)-1,3-dithiane, and2-lithio-2-(4-dibutylaminophenyl)-1,3-dithiane,2-lithio-[4-(4-methylpiperazino)]phenyl-1,3-dithiane,2-lithio-[2-(4-methylpiperazino)]phenyl-1,3-dithiane,2-lithio-[2-morpholino]phenyl-1,3-dithiane,2-lithio-[4-morpholin-4-yl]phenyl-1,3-dithiane,2-lithio-[2-morpholin-4-yl-pyridine-3]-1,3-dithiane,2-lithio-[6-morpholin-4-pyridino-3]-1,3-dithiane,2-lithio-[4-methyl-3,4-dihydro-2H-1,4-benzoxazine-7]-1,3-dithiane, andmixtures thereof.

The amount of initiator required to effect the desired polymerizationcan be varied over a wide range depending upon a number of factors, suchas the desired polymer molecular weight and the desired physicalproperties for the polymer produced. In general, the amount of initiatorutilized can vary from as little as 0.1 millimoles (mM) of lithium per100 grams of monomers up to 100 mM of lithium per 100 grams of monomers,depending upon the desired polymer molecular weight.

Polymerization is usually conducted in a conventional solvent foranionic polymerizations, such as hexane, cyclohexane, benzene and thelike. Various techniques for polymerization, such as batch, semi-batchand continuous polymerization can be employed.

Polymerization can be begun by charging a blend of the monomer(s) andsolvent to a suitable reaction vessel, followed by the addition of thecomposition containing the at least one oxolanyl compound and theinitiator previously described. The procedure is carried out underanhydrous, anaerobic conditions. Often, it is conducted under a dry,inert gas atmosphere. The polymerization can be carried out at anyconvenient temperature, such as −78° C. to 150° C. For batchpolymerizations, it is suitable to maintain the peak temperature at from50° C. to 150° C. and, also suitably, from 80° C. to 130° C.Polymerization may be allowed to continue under agitation for variousamounts of time, such as 0.15 hours to 24 hours. After polymerization iscomplete, the product is terminated by a quenching agent, an endcappingagent and/or a coupling agent, as described herein below. Theterminating agent is added to the reaction vessel, and the vessel isagitated for 0.1 hours to 4.0 hours. Quenching is usually conducted bystirring the polymer and quenching agent for 0.01 hours to 1.0 hour attemperatures of from 20° C. to 120° C. to ensure a complete reaction.

To terminate the polymerization, and thus further control polymermolecular weight, a terminating agent, coupling agent or linking agentmay be employed, all of these agents being collectively referred toherein as “terminating reagents.” Useful terminating, coupling orlinking agents include active hydrogen compounds such as water oralcohol. Certain of these reagents may provide the resulting polymerwith multifunctionality. That is, the (co)polymer may carry a functionalhead group from the initiator, and may also carry a second functionalgroup as a result of the terminating reagents, coupling agents andlinking agents used in the polymer synthesis. Useful functionalizingagents include those conventionally employed in the art.

Examples of useful terminating reagents include active hydrogencompounds such as water or alcohols (e.g., isopropyl alcohol and methylalcohol); benzophenones; benzaldehydes; imidazolidones; pyrrolidinones;carbodimides; N-cyclic amides; ureas; N,N-disubstituted cyclic ureas;cyclic amides; cyclic ureas; isocyanates; Schiff-bases, including thosedisclosed in U.S. Pat. Nos. 3,109,871, 3,135,716, 5,332,810, 5,109,907,5,210,145, 5,227,431, 5,329,005, 5,935,893, which are incorporatedherein by reference; 4,4′bis(diethylamino)benzophenone; alkylthiothiazolines; substituted aldimines; substituted ketimines; Michler'sketone; 1,3-dimethyl-2-imidazolidinone; 1-alkyl substitutedpyrrolidinones; 1-aryl substituted pyrrolidinones;N,N-dialkylamino-benzaldehyde (such as dimethylaminobenzaldehyde or thelike); 1,3-dialkyl-2-imidazolidinones (such as1,3-dimethyl-2-imidazolidinone or the like); 1-alkyl substitutedpyrrolidinones; 1-aryl substituted pyrrolidinones; tin tetrachloride;trialkyltin halides such as tributyltin chloride, as disclosed in U.S.Pat. Nos. 4,519,431, 4,540,744, 4,603,722, 5,248,722, 5,349,024,5,502,129, and 5,877,336, which are incorporated herein by reference;cyclic amino compounds such as hexamethyleneimine alkyl chloride, asdisclosed in U.S. Pat. Nos. 5,786,441, 5,916,976 and 5,552,473, whichare incorporated herein by reference; cyclic sulfur-containing or oxygencontaining azaheterocycles such as disclosed in U.S. Publication No.2006/0074197 A1, U.S. Publication No. 2006/0178467 A1 and U.S. Pat. No.6,596,798, which are incorporated herein by reference; boron-containingterminators such as disclosed in U.S. Pat. No. 7,598,322, which isincorporated herein by reference. Further, other examples includeα-halo-ω-amino alkanes, such as1-(3-bromopropyl)-2,2,5,5-tetramethyl-1-aza-2,5-disilacyclopentane,including those disclosed in copending U.S. Publication Nos.2007/0293620 A1 and 2007/0293620 A1, which are incorporated herein byreference. Other examples include N-substituted aminoketones,N-substituted thioaminoketones, N-substituted aminoaldehydes, andN-substituted thioaminoaldehydes, including N-methyl-2-pyrrolidone ordimethylimidazolidinone (i.e., 1,3-dimethylethyleneurea) as disclosed inU.S. Pat. Nos. 4,677,165, 5,219,942, 5,902,856, 4,616,069, 4,929,679,5,115,035, and 6,359,167, which are incorporated herein by reference;carbon dioxide; and mixtures thereof. Further examples of reactivecompounds include the terminators described in co-owned U.S. Pat. Nos.5,521,309, 5,502,131, 5,496,940, 5,066,729, and 4,616,069, the subjectmatter of which, pertaining to terminating agents and terminatingreactions, is hereby incorporated by reference. Other useful terminatingreagents can include those of the structural formula (R)_(a)ZX_(b),where Z is tin or silicon. Z is most suitably tin. R is an alkyl havingfrom 1 to 20 carbon atoms; a cycloalkyl having from 3 to 20 carbonatoms; an aryl having from 6 to 20 carbon atoms, or an aralkyl havingfrom 7 to 20 carbon atoms. For example, R can include methyl, ethyl,n-butyl, neophyl, phenyl, cyclohexyl or the like. X is a halogen, suchas chlorine or bromine, or alkoxy (—OR), “a” is an integer from zero to3, and “b” is an integer from one to 4, where a+b=4. Examples of suchterminating agents include tin tetrachloride, tributyl tin chloride,butyl tin trichloride, butyl silicon trichloride, as well astetraethylorthosilicate (TEOS), Si(OEt)₄, and methyl triphenoxysilane,MeSi(OPh)₃. Other agents include the alkoxy silanes Si(OR)₄, RSi(OR)₃,R₂Si(OR)₂, cyclic siloxanes (such as hexamethylcyclotrisiloxane,including those disclosed in copending U.S. Publication No. 2007/0149744A1, which is incorporated herein by reference), and, mixtures thereof.The organic moiety R is selected from the group consisting of alkylshaving from 1 to 20 carbon atoms, cycloalkyls having from 3 to 20 carbonatoms, aryls having from 6 to 20 carbon atoms and aralkyls having from 7to 20 carbon atoms. Typical alkyls include n-butyl, s-butyl, methyl,ethyl, isopropyl and the like. The cycloalkyls include cyclohexyl,menthyl and the like. The aryl and the aralkyl groups include phenyl,benzyl and the like.

In certain embodiments, the living polymer can be treated with bothcoupling and functionalizing agents, which serve to couple some chainsand functionalize other chains. The combination of coupling agent andfunctionalizing agent can be used at various molar ratios. Although theterms coupling and functionalizing agents have been employed in thisspecification, those skilled in the art appreciate that certaincompounds may serve both functions. That is, certain compounds may bothcouple and provide the polymer chains with a functional group. Thoseskilled in the art also appreciate that the ability to couple polymerchains may depend upon the amount of coupling agent reacted with thepolymer chains. For example, advantageous coupling may be achieved wherethe coupling agent is added in a one to one ratio between theequivalents of lithium on the initiator and equivalents of leavinggroups (e.g., halogen atoms) on the coupling agent.

Exemplary coupling agents include metal halides, metalloid halides,alkoxysilanes, and alkoxystannanes.

In one or more embodiments, useful metal halides or metalloid halidesmay be selected from the group comprising compounds expressed by theformula (1) R¹ _(n)M¹X_(4-n), the formula (2) M¹X₄, and the formula (3)M²X₃, where R¹ is the same or different and represents a monovalentorganic group with carbon number of 1 to about 20, M¹ in the formulas(1) and (2) represents a tin atom, silicon atom, or germanium atom, M²represents a phosphorous atom, X represents a halogen atom, and nrepresents an integer of 0-3.

Exemplary compounds expressed by the formula (1) include halogenatedorganic metal compounds, and the compounds expressed by the formulas (2)and (3) include halogenated metal compounds.

In the case where M¹ represents a tin atom, the compounds expressed bythe formula (1) can be, for example, triphenyltin chloride, tributyltinchloride, triisopropyltin chloride, trihexyltin chloride, trioctyltinchloride, diphenyltin dichloride, dibutyltin dichloride, dihexyltindichloride, dioctyltin dichloride, phenyltin trichloride, butyltintrichloride, octyltin trichloride and the like. Furthermore, tintetrachloride, tin tetrabromide and the like can be exemplified as thecompounds expressed by formula (2).

In the case where M¹ represents a silicon atom, the compounds expressedby the formula (1) can be, for example, triphenylchlorosilane,trihexylchlorosilane, trioctylchlorosilane, tributylchlorosilane,trimethylchlorosilane, diphenyldichlorosilane, dihexyldichlorosilane,dioctyldichlorosilane, dibutyldichlorosilane, dimethyldichlorosilane,methyltrichlorosilane, phenyltrichlorosilane, hexyltrichlorosilane,octyltrichlorosilane, butyltrichlorosilane, methyltrichlorosilane andthe like. Furthermore, silicon tetrachloride, silicon tetrabromide andthe like can be exemplified as the compounds expressed by the formula(2). In the case where M¹ represents a germanium atom, the compoundsexpressed by the formula (1) can be, for example, triphenylgermaniumchloride, dibutylgermanium dichloride, diphenylgermanium dichloride,butylgermanium trichloride and the like. Furthermore, germaniumtetrachloride, germanium tetrabromide and the like can be exemplified asthe compounds expressed by the formula (2). Phosphorous trichloride,phosphorous tribromide and the like can be exemplified as the compoundsexpressed by the formula (3). In one or more embodiments, mixtures ofmetal halides and/or metalloid halides can be used.

In one or more embodiments, useful alkoxysilanes or alkoxystannanes maybe selected from the group comprising compounds expressed by the formula(1) R¹ _(n)M¹(OR)_(4-n), where R¹ is the same or different andrepresents a monovalent organic group with carbon number of 1 to about20, M¹ represents a tin atom, silicon atom, or germanium atom, ORrepresents an alkoxy group where R represents a monovalent organicgroup, and n represents an integer of 0-3.

Exemplary compounds expressed by the formula (4) include tetraethylorthosfficate, tetramethyl orthosilicate, tetrapropyl orthosilicate,tetraethoxy tin, tetramethoxy tin, and tetrapropoxy tin.

The amount of terminating agent required to effect the desiredtermination of the polymerization can be varied over a wide rangedepending upon a number of factors, such as the desired polymermolecular weight and the desired physical properties for the polymerproduced. In general, the amount of terminating agent utilized can varyfrom a molar ratio of 0.1:5 to 0.5:1.5 to 0.8:1.2 (terminating agent:Li).

The practice of polymerization processes described herein is not limitedsolely to the terminating reagents described herein, since othercompounds that are reactive with the polymer bound carbon-lithium moietycan be selected to provide a desired functional group. In other words,the foregoing listing of terminating reagents is not to be construed aslimiting but rather as enabling. While a terminating reagent can beemployed, practice of the present embodiments are not limited to aspecific reagent or class of such compounds.

While terminating to provide a functional group on the terminal end ofthe polymer is desirable, it is further desirable to terminate by acoupling reaction with, for example, tin tetrachloride or other couplingagent such as silicon tetrachloride or esters. High levels of tincoupling are desirable in order to maintain good processability in thesubsequent manufacturing of rubber products. It is preferred that thepolymers for use in the vulcanizable elastomeric compositions accordingto the present embodiments have at least 25 percent tin coupling. Thatis, 25 percent of the polymer mass after coupling is of higher molecularweight than the polymer before coupling as measured, for example, by gelpermeation chromatography. Suitably, before coupling, the polydispersity(the ratio of the weight average molecular weight to the number averagemolecular weight) of polymers, which can be controlled over a widerange, is preferably less than 2, more preferably less than 1.5, andeven more preferably less than 1.3.

As noted above, various techniques known in the art for carrying out thepolymerization processes described herein can be used to producepolydiene (co)polymers, without departing from the scope of the presentembodiments.

In additional embodiments the polymerization process comprisingpolymerizing 1,3-butadiene in the presence of the oxolanyl compound2,2-di(2-tetrahydrofuryl)propane where the oxolanyl compound comprisesat least 52% by weight of the meso-isomer. Such a process produces apolydiene polymer with a vinyl content between 20 and 65%, includes theuse of an organolithium anionic initiator, and is conducted at atemperature between 85° C. and 120° C.

The (co)polymers prepared utilizing the compositions and processesdisclosed herein are particularly useful for use in preparing tirecomponents (e.g., treads and sidewalls). Such tire components can beprepared by using such (co)polymers alone or together with other rubberypolymers or elastomers. Preferably, the (co)polymers are employed intread formulations, and these tread formulations will include from 10 to100% by weight of the (co)polymer based on the total rubber within theformulation (i.e., 10 to 100 parts of the (co)polymer(s) per 100 partsof total rubber or phr). More preferably, the tread formulation willinclude from 35 to 80% by weight, and more preferably from 50 to 80% byweight of the (co)polymer based on the total weight of the rubber withinthe formulation.

In preparing the vulcanizable compositions of matter (or rubbercompositions) containing the co(polymers) prepared utilizing thecompositions and processes disclosed herein, and optionally, one or moreother rubber polymers, at least one filler may be combined and mixed orcompounded with a rubber component, which includes the (co)polymersdisclosed herein as well as other optional rubber polymers. Otherrubbery elastomers or polymers that may be used include natural andsynthetic elastomers. The synthetic elastomers typically derive from thepolymerization of conjugated diene monomers. These conjugated dienemonomers may be copolymerized with other monomers such as vinyl aromaticmonomers. Other rubbery elastomers may derive from the polymerization ofethylene together with one or more α-olefins and optionally one or morediene monomers.

Useful rubbery elastomers include, but are not limited to, naturalrubber, synthetic polyisoprene, polybutadiene,polyisobutylene-co-isoprene, neoprene, poly(ethylene-co-propylene),poly(styrene-co-butadiene), poly(styrene-co-isoprene), andpoly(styrene-co-isoprene-co-butadiene), poly(isoprene-co-butadiene),poly(ethylene-co-propylene-co-diene), polysulfide rubber, acrylicrubber, urethane rubber, silicone rubber, epichlorohydrin rubber, andmixtures thereof. These elastomers can have a myriad of macromolecularstructures including linear, branched and star shaped. Other ingredientsthat are typically employed in rubber compounding may also be added.

The rubber compositions may include fillers such as inorganic andorganic fillers. Commonly utilized organic fillers include carbon blackand starch. Commonly utilized inorganic fillers include silica, aluminumhydroxide, magnesium hydroxide, clays (hydrated aluminum silicates), andmixtures thereof.

In one or more embodiments, silica (silicon dioxide) includeswet-process, hydrated silica produced by a chemical reaction in water,and precipitated as ultra-fine spherical particles. In one embodiment,the silica has a surface area of about 32 to about 400 m²/g, in anotherembodiment about 100 to about 250 m²/g, and in yet another embodiment,about 150 to about 220 m²/g. The pH of the silica filler in oneembodiment is about 5.5 to about 7 and in another embodiment about 5.5to about 6.8. Commercially available silicas include Hi-Sil™ 215,Hi-Sil™ 233, Hi-Sil™ 255LD, and Hi-Sil™ 190 (PPG Industries; Pittsburgh,Pa.), Zeosil™ 1165MP and 175GRPlus (Rhodia), Vulkasil™ (Bary AG),Ultrasil™ VN2, VN3 (Degussa), and HuberSil™ 8745 (Huber).

In one or more embodiments, the carbon blacks may include any of thecommonly available, commercially-produced carbon blacks. These includethose having a surface area (EMSA) of at least 20 m²/gram and in otherembodiments at least 35 m²/gram up to 200 m²/gram or higher. Surfacearea values include those determined by ASTM test D-1765 using thecetyltrimethyl-ammonium bromide (CTAB) technique. Among the usefulcarbon blacks are furnace black, channel blacks and lamp blacks. Morespecifically, examples of the carbon blacks include super abrasionfurnace (SAF) blacks, high abrasion furnace (HAF) blacks, fast extrusionfurnace (FEF) blacks, fine furnace (FF) blacks, intermediate superabrasion furnace (ISAF) blacks, semi-reinforcing furnace (SRF) blacks,medium processing channel blacks, hard processing channel blacks andconducting channel blacks. Other carbon blacks that may be utilizedinclude acetylene blacks. Mixtures of two or more of the above blackscan be used. Exemplary carbon blacks include those bearing ASTMdesignation (D-1765-82a) N-110, N-220, N-339, N-330, N-351, N-550, andN-660. In one or more embodiments, the carbon black may include oxidizedcarbon black.

In one embodiment, silica may be used in an amount of from about 5 toabout 100 parts by weight parts per hundred rubber (phr), in anotherembodiment from about 10 to about 90 parts by weight phr, in yet anotherembodiment from about 15 to about 80 parts by weight phr, and in stillanother embodiment from about 25 to about 75 parts by weight phr.

As is well-known to those of skill in the art, a multitude of rubbercuring agents may be employed. For example, sulfur or peroxide-basedcuring systems may be employed. Also, see Kirk-Othmer, ENCYCLOPEDIA OFCHEMICAL TECHNOLOGY, 3^(rd) Edition, Wiley Interscience, New York 1982,Vol. 20, pp. 365-468, particularly VULCANIZATION AGENTS AND AUXILIARYMATERIALS pp. 390-402, or Vulcanization by A. Y. Coran, ENCYCLOPEDIA OFPOLYMER SCIENCE AND ENGINEERING, 2^(nd) Edition, John Wiley & Sons,Inc., 1989, which are incorporated herein by reference. Vulcanizingagents may be used alone or in combination. In one or more embodiments,the preparation of vulcanizable compositions and the construction andcuring of the tire is not affected.

Other ingredients that may be employed are also well known to those ofskill in the art and include accelerators, oils, waxes, scorchinhibiting agents, processing aids, zinc oxide, tackifying resins,reinforcing resins, fatty acids such as stearic acid, peptizers, and oneor more additional rubbers. Examples of oils include paraffinic oils,aromatic oils, naphthenic oils, vegetable oils other than castor oils,and low PCA oils including MES, TDAE, SRAE, heavy naphthenic oils, andblack oils.

In one or more embodiments, the vulcanizable rubber composition may beprepared by forming an initial masterbatch that includes the rubbercomponent and filler (the rubber component optionally including otherpolymers and rubbery polymers such as functional polymers). This initialmasterbatch may be mixed at a starting temperature of from about 25° C.to about 125° C. with a discharge temperature of about 135° C. to about180° C. To prevent premature vulcanization (also known as scorch), thisinitial masterbatch may exclude vulcanizing agents. Once the initialmasterbatch is processed, the vulcanizing agents may be introduced andblended into the initial masterbatch at low temperatures in a final mixstage, which preferably does not initiate the vulcanization process.Optionally, additional mixing stages, sometimes called remills, can beemployed between the masterbatch mix stage and the final mix stage.Various ingredients including polymers and copolymers can be addedduring these remills. Rubber compounding techniques and the additivesemployed therein are generally known as disclosed in The Compounding andVulcanization of Rubber, in Rubber Technology (2nd Ed. 1973).

The mixing conditions and procedures applicable to silica-filled tireformulations are also well known as described in U.S. Pat. Nos.5,227,425, 5,719,207, 5,717,022, and European Patent No. 890,606, all ofwhich are incorporated herein by reference. In one or more embodiments,where silica is employed as a filler (alone or in combination with otherfillers), a coupling and/or shielding agent may be added to the rubberformulation during mixing. Useful coupling and shielding agents aredisclosed in U.S. Pat. Nos. 3,842,111, 3,873,489, 3,978,103, 3,997,581,4,002,594, 5,580,919, 5,583,245, 5,663,396, 5,674,932, 5,684,171,5,684,172 5,696,197, 6,608,145, 6,667,362, 6,579,949, 6,590,017,6,525,118, 6,342,552, and 6,683,135, which are incorporated herein byreference. In one embodiment, the initial masterbatch is prepared byincluding the rubbery polymers and/or copolymers and silica in thesubstantial absence of coupling and shielding agents. It is believedthat this procedure will enhance the opportunity that a functionalpolymer will react or interact with silica before competing withcoupling or shielding agents, which can be added later curing remills.

Where the vulcanizable rubber compositions are employed in themanufacture of tires, these compositions can be processed into tirecomponents according to ordinary tire manufacturing techniques includingstandard rubber shaping, molding and curing techniques. Any of thevarious rubber tire components can be fabricated including, but notlimited to, treads, sidewalls, belt skims, and carcass. Typically,vulcanization is effected by heating the vulcanizable composition in amold; e.g., it may be heated to about 140° C. to about 180° C. Cured orcrosslinked rubber compositions may be referred to as vulcanizates,which generally contain three-dimensional polymeric networks that arethermoset. The other ingredients, such as processing aides and fillers,may be evenly dispersed throughout the vulcanized network. Pneumatictires can be made as discussed in U.S. Pat. Nos. 5,866,171, 5,876,527,5,931,211, and 5,971,046, which are incorporated herein by reference.

This application discloses several numerical range limitations thatsupport any range within the disclosed numerical ranges even though aprecise range limitation is not stated verbatim in the specificationbecause the embodiments could be practiced throughout the disclosednumerical ranges. With respect to the use of substantially any pluraland/or singular terms herein, those having skill in the art cantranslate from the plural to the singular and/or from the singular tothe plural as is appropriate to the context and/or application. Thevarious singular/plural permutations may be expressly set forth hereinfor sake of clarity.

It will be understood by those within the art that, in general, termsused herein, and especially in the appended claims (e.g., bodies of theappended claims) are generally intended as “open” terms (e.g., the term“including” should be interpreted as “including but not limited to,” theterm “having” should be interpreted as “having at least,” the term“includes” should be interpreted as “includes but is not limited to,”etc.). It will be further understood by those within the art that if aspecific number of an introduced claim recitation is intended, such anintent will be explicitly recited in the claim, and in the absence ofsuch recitation no such intent is present. For example, as an aid tounderstanding, the following appended claims may contain usage of theintroductory phrases “at least one” and “one or more” to introduce claimrecitations. However, the use of such phrases should not be construed toimply that the introduction of a claim recitation by the indefinitearticles “a” or “an” limits any particular claim containing suchintroduced claim recitation to inventions containing only one suchrecitation, even when the same claim includes the introductory phrases“one or more” or “at least one” and indefinite articles such as “a” or“an” (e.g., “a” and/or “an” should typically be interpreted to mean “atleast one” or “one or more”); the same holds true for the use ofdefinite articles used to introduce claim recitations. In addition, evenif a specific number of an introduced claim recitation is explicitlyrecited, those skilled in the art will recognize that such recitationshould typically be interpreted to mean at least the recited number(e.g., the bare recitation of “two recitations,” without othermodifiers, typically means at least two recitations, or two or morerecitations). Furthermore, in those instances where a conventionanalogous to “at least one of A, B, and C, etc.” is used, in generalsuch a construction is intended in the sense one having skill in the artwould understand the convention (e.g., “a system having at least one ofA, B, and C” would include but not be limited to systems that have Aalone, B alone, C alone, A and B together, A and C together, B and Ctogether, and/or A, B, and C together, etc.). In those instances where aconvention analogous to “at least one of A, B, or C, etc.” is used, ingeneral such a construction is intended in the sense one having skill inthe art would understand the convention (e.g., “a system having at leastone of A, B, or C” would include but not be limited to systems that haveA alone, B alone, C alone, A and B together, A and C together, B and Ctogether, and/or A, B, and C together, etc.). It will be furtherunderstood by those within the art that virtually any disjunctive wordand/or phrase presenting two or more alternative terms, whether in thedescription, claims, or drawings, should be understood to contemplatethe possibilities of including one of the terms, either of the terms, orboth terms. For example, the phrase “A or B” will be understood toinclude the possibilities of “A” or “B” or “A and B.”

All references, including but not limited to patents, patentapplications, and non-patent literature are hereby incorporated byreference herein in their entirety.

While various aspects and embodiments have been disclosed herein, otheraspects and embodiments will be apparent to those skilled in the art.The various aspects and embodiments disclosed herein are for purposes ofillustration and are not intended to be limiting, with the true scopeand spirit being indicated by the claims.

EXAMPLES Isolation of the Diastereoisomers of2,2-di(2-tetrahydrofuryl)propane

A commercially obtained quantity of 2,2-di(2-tetrahydrofuryl)propane(Penn Specialty Chemicals) was purified using column chromotography toisolate the diastereoisomers. The column was prepared with a stationaryphase of 230-400 mesh size silica gel (available from Fisher Scientific)and a mobile phase of 20% diethyl ether and 80% n-pentane. Repeated 25mL aliquots of the mobile phase were utilized. Puremeso-2,2-di(2-tetrahydrofuryl)propane was isolated as a first fraction.The yield of the meso-isomer was approximately 20% of the originalamount of 2,2-di(2-tetrahydrofuryl)propane. PureD,L-2,2-di(2-tetrahydrofuryl)propane was isolated as the second fractionand the yield was also approximately 20% of the original amount of2,2-di(2-tetrahydrofuryl)propane. GC-FID analysis (of the starting2,2-di(2-tetrahydrofuryl)propane and the two diastereoisomers confirmedthe purity of the first two fractions. Conditions included: Use ofSupelco Equity 1 column (30 m×0.32 mm×5.0 μm); GC-Injection porttemperature: 260° C.; Injection Port split ratio: 20:1; carrier gas ranin the constant flow mode with 1.5 mL/minute; FID temperature: 280° C.;sample size: 1 μl. Column Oven Program:

Rate ° C./min Temperature/° C. Time/min Total/min Initial 55 1.0 1.0 10280 12.5 36.0Structures were also confirmed by ¹H-NMR (as illustrated in FIGS. 3 and4). In FIG. 3, note the two peaks for methyls indicating the meso form.In FIG. 4, note the one peak for the methyls indicating D, L form.Polymerization of 1,3-Butadiene

To an 800 mL nitrogen-purged bottle fitted with a crimp seal cap wasadded 183.5 g of 21.8 weight percent 1,3-butadiene in hexanes, 0.24 mL1.65 M n-butyllithium in hexanes, and a varying amount (Table 1, below)of meso, DL or a commercially available 2,2-di(2-tetrahydrofuryl)propane(containing 51% by weight of the meso isomer and approximately 49% byweight of the D and L isomers and indicated below as “mixed”). Thebottle was then placed in a 50° C. bath for 4 hours. Concentration ofthe 2,2-di(2-tetrahydrofuryl)propane (“DTHFP”) was measured by GC, vinylcontent by ¹H-NMR, and molecular weight by GPC using the appropriateMark Houwink constant (polystyrene standard).

Properties of the resulting polymers are listed in Table 1 and a plot ofconcentration of the oxolanyl compound versus % vinyl content in theresulting polybutadiene is shown in FIG. 1. The meso form of theoxolanyl compound was more effective in producing vinyl content thateither the mixture of the DL form. In other words, a relatively lesseramount of the meso form was needed to produce the same vinyl content.

TABLE 1 Concentration % Vinyl in Mn (kg/mol) of Type (ppm) ResultingPolymer Resulting Polymer Mixed 26 30.2 93.0 Mixed 66 47.1 88.5 Mixed 7346.4 106.0 Mixed 81 50.7 94.4 Mixed 134 60.1 94.2 Mixed 147 58.2 100.6Mixed 350 71.4 96.3 Meso 44 46.4 91.4 Meso 66 54.1 90.0 Meso 109 58.8102.8 Meso 224 67.1 105.6 D, L 42 29 89.8 D, L 44 31.6 107.3 D, L 8342.1 94.4 D, L 89 44.6 94.4 D, L 108 50.5 93.4Polymerization of 1,3-Butadiene and Styrene

To an 800 mL nitrogen-purged bottle fitted with a crimp seal cap wasadded 23.5 g of 34 weight percent styrene in hexanes and 14.35 g of 22.3weight percent 1,3-butadiene in hexanes, 0.24 mL 1.65 M n-butyllithiumin hexanes, and a varying amount (Table 2, below) of meso (100% meso),pure DL (100% DL) or a commercially available2,2-di(2-tetrahydrofuryl)propane (containing approximately 50% by weightof the meso isomer and approximately 50% by weight of the D and Lisomers and indicated below as “mixed”). The bottle was then placed in a50° C. bath for 4 hours. Concentration of the2,2-di(2-tetrahydrofuryl)propane was measured by GC, vinyl content by¹H-NMR, and molecular weight by GPC using the appropriate Mark Houwinkconstant (polystyrene standard).

Properties of the resulting polymers are listed in Table 2 and a plot ofconcentration of the oxolanyl compound versus % vinyl content in theresulting polybutadiene is shown in FIG. 2. Again, the meso form of theoxolanyl compound was more effective in producing vinyl content thateither the mixture of the DL form. In other words, a relatively lesseramount of the meso form was needed to produce the same vinyl content.

TABLE 2 Concentration % Vinyl in Mn (kg/mol) of Type (ppm) ResultingPolymer Resulting Polymer Mixed 71 45.6 104.9 Mixed 71 47.6 99.5 Mixed145 55.2 99.2 Meso 107 57.1 97.5 D, L 42 30.9 100 D, L 79 42.0 104.4Influence of Meso/D,L DTHFP on Vinyl in Polybutadiene Polymerization

To an 800 mL nitrogen purged bottle was added 214 g hexanes and 186 g of21.5 wt % butadiene in hexanes. Then, either 0.08 mL, 0.15 mL, 0.30 mL,0.60 mL, or 1.0 mL of approximately 0.4 M 2,2-ditetrahydrofurylpropaneof varying meso concentrations (99.8%, 88.1%, 87.3%, 75%, 65.3%, 54.9%,44.9%, and 5.8%) was added. Afterwards, 0.24 mL of 1.65 M n-butyllithiumin hexanes was added and the bottles were heated to 50° C. for fourhours. ¹H NMR was used to determine vinyl content in the polybutadienesamples and GC was used to determine the concentration of2,2-ditetrahydrofurylpropane.

Properties of the resulting polymers are listed in Table 3 and a plot ofvinyl content as a function of ppm DTHFP at various Meso DTHFPconcentrations is shown in FIG. 5.

TABLE 3 % Meso DTHFP ppm DTHFP % Vinyl 99.8 14.00 17.3 99.8 17.14 21.799.8 40.13 42.5 99.8 83.58 58.1 99.8 135.74 67.8 88.1 11.60 17.9 88.123.39 28.5 88.1 49.98 42.8 88.1 96.04 58.5 88.1 176.70 67.8 87.3 23.1524 87.3 28.53 29.2 87.3 56.89 42.7 87.3 103.13 57.5 87.3 172.60 66.2 7511.42 20.1 75 44.29 36.3 75 53.58 42.2 75 109.94 57.4 75 176.01 68 65.37.52 13.9 65.3 22.55 25.6 65.3 49.98 39.2 65.3 90.14 54.7 65.3 147.6063.7 54.9 11.94 17 54.9 17.85 21.6 54.9 39.86 34.2 54.9 88.82 49.2 54.9154.06 59.9 44.9 13.75 16.8 44.9 24.55 23.5 44.9 47.26 35.8 44.9 103.4550.7 44.9 155.57 61.3 5.8 12.34 17.1 5.8 28.73 22.1 5.8 54.30 31.6 5.898.51 44.3 5.8 170.81 53.9Kinetics of Polybutadiene Polymerization

The rate of anionic butadiene polymerization was next examined forpolymerization modified in the presence of 99.8% meso2,2-ditetrahydrofurylpropane and 49.7% meso2,2-ditetrahydrofurylpropane.

Butadiene Polymerization Rate Utilizing 99.8%Meso-2,2-Ditetrahydrofurylpropane

To a 7.57 L nitrogen purged, stainless steel reactor was added 0.54 kgof anhydrous hexanes and 1.63 kg of 20.9 weight percent 1,3-butadiene inhexanes. Then, 5.73 mL of 0.36 M 2,2-ditetrahydrofurylpropane (99.8%meso) in hexanes and 1.37 mL 1.65 M butyl lithium in hexanes was addedat 11.7° C. (The 99.8% meso 2,2-ditetrahydrofurylpropane was isolatedusing the column chromotography procedure described above.) The reactorjacket was set at 71.1° C. Samples were taken at 5, 10, 15, 20, 25, 30,45, 60, and 90 minutes and measured for conversion and molecular weight.Samples at 20, 30 and 60 minutes were examined for vinyl content by ¹HNMR. GC was used to measure the concentration of 1,3-butadiene and2,2-ditetrahydrofurylpropane (124 ppm) in the reaction.

Properties of the resulting polymers, from samples taken at theindicated reaction times, are listed in Table 4 and a plot showing theweight percent butadiene of the reaction mixture over time and thetemperature of the reaction mixture over time is shown in FIG. 6. Thedashed lines of FIG. 6 plot the weight percent butadiene of the reactionmixture over time and the solid lines of FIG. 6 plot the temperature ofthe reaction mixture over time.

TABLE 4 Reaction Time Weight Percent Molecular Weight (minutes)Butadiene (kg/mol) % Vinyl 5 10.51 8.2 10 9.72 27.5 15 5.85 56.9 20 2.1392 55.2 25 0.6 103.2 30 0.21 106.9 52.1 45 0.12 111.4 60 0.18 114.2 51.790 0.03 117.9Butadiene Polymerization Rate Utilizing 49.7%meso-2,2-Ditetrahydrofurylpropane

To a 7.57 L nitrogen purged, stainless steel reactor was added 0.54 kgof anhydrous hexanes and 1.63 kg of 20.9 weight percent 1,3-butadiene inhexanes. Then, 0.82 mL of 1.6 M 2,2-ditetrahydrofurylpropane (49.7%meso) in hexanes and 1.37 mL 1.65 M butyl lithium in hexanes were addedat 12.1° C. (The 49.7% meso 2,2-ditetrahydrofurylpropane was used asreceived from the supplier.) The reactor jacket was set at 71.1° C.Samples were taken at 5, 10, 15, 20, 25, 30, 45, 60, and 90 minutes andmeasured for conversion and molecular weight. Samples taken at 20, 30and 60 minutes were examined for vinyl content by ¹H NMR. GC was used tomeasure the concentration of 1,3-butadiene and2,2-ditetrahydrofurylpropane (176 ppm) in the reaction.

Properties of the resulting polymers are listed in Table 5 and a plotshowing the weight percent butadiene of the reaction mixture over timeand the temperature of the reaction mixture over time is shown in FIG.6. The dashed lines of FIG. 6 plot the weight percent butadiene of thereaction mixture over time and the solid lines of FIG. 6 plot thetemperature of the reaction mixture over time.

TABLE 5 Reaction Time Weight Percent Molecular Weight (minutes)Butadiene (kg/mol) % Vinyl 5 9.59 10 9 31.9 15 5.23 64.6 20 1.5 95.852.6 25 0.4 106.9 30 0.17 110 50 45 0.1 112.1 60 0.06 114.6 49.8 90 0.03118.6The experimental examples show that as the meso content increases atconstant DTHFP concentration, the vinyl content of the resulting polymerincreases. The last two experimental examples show that with reactorruns using approximately 60% of 99.8% meso DTHFP (124 ppm) gives similarvinyl to using 100% of a ˜50% meso DTHFP (176 ppm).

We claim:
 1. A polymerization process comprising the step ofpolymerizing at least one conjugated diene monomer in the presence of ananionic initiator and a composition comprising at least one oxolanylcompound selected from the group consisting of:

wherein R₁ and R₂ independently are hydrogen or an alkyl group and thetotal number of carbon atoms in —CR₁R₂— ranges between one and nineinclusive; R₃, R₄ and R₅ independently are —H or —C_(n)H_(2n+1) whereinn=1 to 6, wherein at least 60% by weight of the least one oxolanylcompound comprises meso-isomer and the process produces a polydienepolymer having a vinyl microstructure content of at least about 20%. 2.The process of claim 1, wherein the initiator comprises anorganometallic initiator and is utilized in an amount of about 0.1millimoles of metal per 100 grams of monomer to about 100 millimoles ofmetal per 100 grams of monomer.
 3. The process of claim 1, wherein themeso-isomer is used in an amount such that the molar ratio of themeso-isomer to the initiator is from about 0.001:1 to about 1:1.
 4. Theprocess of claim 1, wherein at least 75% by weight of the at least oneoxolanyl compound comprises meso-isomer.
 5. The process of claim 1,wherein at least about 80% by weight of the at least one oxolanylcompound comprises meso-isomer.
 6. The process of claim 1, wherein atleast about 90% by weight of the at least one oxolanyl compoundcomprises meso-isomer.
 7. The process of claim 1 where the producedpolydiene polymer has a vinyl microstructure content of at least about30%.
 8. The process of claim 2, where the produced polydiene polymer hasa vinyl microstructure content of at least about 30%.
 9. The process ofclaim 3, where the produced polydiene polymer has a vinyl microstructurecontent of at least about 30%.
 10. The process of claim 4, where theproduced polydiene polymer has a vinyl microstructure content of atleast about 30%.
 11. The process of claim 5, where the producedpolydiene polymer has a vinyl microstructure content of at least about30%.
 12. The process of claim 6, where the produced polydiene polymerhas a vinyl microstructure content of at least about 30%.
 13. Theprocess of claim 1, further comprising the step of polymerizing at leastone vinyl aromatic monomer.
 14. The process of claim 13 wherein the atleast one vinyl aromatic monomer is selected from the group consistingof styrene, a-methyl styrene, p-methylstyrene, vinylnaphthalene, andmixtures thereof.
 15. The process of claim 1, wherein the at least oneconjugated diene monomer is selected from the group consisting of1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene,1,3-hexadiene, 2-methyl-1,3-pentadiene, 3,4-dimethyl-1,3-hexadiene,4,5-diethyl-1,3-octadiene, 3-butyl-1,3-octadiene, phenyl-1,3-butadiene,and mixtures thereof.
 16. The process of claim 1 wherein the at leastone anionic initiator is selected from the group consisting oforganolithium, organomagnesium, organosodium, organopotassium, andmixtures thereof.
 17. The process of claim 1 further comprising the useof at least one terminating reagent.
 18. A polymerization processcomprising the step of polymerizing at least one conjugated dienemonomer in the presence of an anionic initiator and a compositioncomprising 2,2-di(2-tetrahydrofuryl)propane, wherein at least 60% byweight of the 2,2-di(2-tetrahydrofuryl)propane comprises meso-isomer andthe process produces a polydiene polymer having a vinyl microstructurecontent of at least 20%.
 19. The process of claim 18 wherein the processfurther comprises polymerizing at least one vinyl aromatic monomer. 20.The process of claim 18, wherein the at least one conjugated dienemonomer comprises 1,3-butadiene.
 21. The process of claim 19, whereinthe at least one conjugated diene monomer comprises 1,3-butadiene andthe at least vinyl aromatic monomer comprises styrene.
 22. The processof claim 18, wherein at least 75% by weight of the at least one oxolanylcompound comprises meso-isomer.
 23. The process of claim 21, wherein atleast 75% by weight of the at least one oxolanyl compound comprisesmeso-isomer.